Give Yahoo a try. You can post comments with only your My Yahoo login, so Facebook isn't necessary. The problem with it is, as I've heard with MSN, that it's very difficult to find your own comments and the replies, so I seldom bother.
When I want to comment on news stories, or join in live discussions on sporting events while they are happening, I head over to Fark.com, where I've been a member for 8 years. There you can discuss all sorts of news, sports or entertainment stories, and they even have a section for discussing politics.
Joining is free, though they do have a $5/month "TotalFark" option that has more "features", but it's not necessary to have a good time in our little community.
There was a problem with Yahoo a few days ago with being unable to find your own comments and replies at the notification part. Is back to normal now.
Agree on the comments here going political. Can read that kind of thing on other sites.